Both sils, rear foot well and main Floor pan, the front of the floor can be dodgy is bad cases, boot floor, normally see rust inside and rust behind the inner wheel arch trim, inner wheel arch on the n/s ,fuel filler neck ;(dirt builds up) inner wheel arch to boot j floor ,o/s inner wing, wings, front crossmember, brake pipes, rear coil mounts top and bottom, tyres (a lot of micra s have old deteriorated tyres) same goes for the front discs and pads, open the glove box and put the heater to recuirulate and see if there is damp in the fan, see if the fan works on all speeds,(simple chip wants doing if otherwise) gear leave tight or slack (seized or women bolt on the linkage) sun roof (drains into the sills) has the car been undersealed (it can be terrible for them) check the slam panel and lights in case it's been bumper, and boot, also on the 51/02 models they used a dodgy rad that falls.apart (it's a frameless design and leaks, may notice some antifreeze , also what's the oil and under the oil cap look like, most micra s don't get serviced right